The objectives of the study are to 1) evaluate the safety and efficacy of two different doses of VIRACEPT compared to placebo, administered for 24 weeks as monotherapy in 90 antiretroviral-naive (<6 months) or reverse transcriptase inhibitor-experienced HIV positive patients who have CD4 cell counts >50 cells/mm3 and quantitative plasma HIV RNA titers of >15,000 copies/ml; 2) to obtain long-term safety and efficacy data on the two active treatment arms; and 3) to assess the potential for viral resistance, by assessing changes in genotype, etc.